This invention relates to polyethylene and to processes for improving polyethylene.
Acrylic polymers are well known as being useful as modifiers for polyvinyl chloride (PVC), for example as processing aids. To those familiar with this art, it is well known that a PVC processing aid and the PVC must be mutually soluble so that blends of the two substances will be clear even though the refractive indices of the two substances are different. Thus if one skilled in the polymer art chose to try to improve the processability of other polymers, for example polypropylene, he would seek a substance which was compatible and eliminate from consideration any modifiers which were incompatible. Thus acrylic polymers, which when blended with polyethylene are incompatible, would be eliminated immediately from consideration as process aids.
Although the prior art (Coover et al., U.S. Pat. No. 3,156,743) does teach that fibers spun from polypropylene and minor amounts of acrylic polymers have improved oxidative degradation resistance, weatherability, and stability to ultraviolet light; i.e., the acrylic polymer is taught to be a stabilizer for polypropylene fiber. However, Coover et al. teach away from use of acrylic polymers in polyethylene because of incompatibility, which made fibers produced from such blends unacceptable and unuseful. Joyner et al., U.S. Pat. No. 3,240,552, teach improving the dyeability of polypropylene fibers by incorporation of acrylic polymer combined with a chelating agent. Sexsmith et al., U.S. Pat. No. 3,228,790, teach aqueous dispersions of colloidal polyolefin and acrylic resins.
None of these references, nor any other prior art, of which I am aware, teach improving the processability of polyethylene by melt blending therewith an acrylic polymer.
It is an object of the present invention to provide a novel polyethylene composition having improved processability.
These and other objects as will become apparent from the description which follows, are achieved by the present invention which comprises a method for improving the processability of polyethylene comprising blending therewith an acrylic polymer and a chelating agent free composition comprising a polyethylene and an acrylic polymer.